Alopecia, the loss of hair in men and women, involves a gradual decrease of scalp hair density in adults, with a transformation of terminal to vellus hairs which become lost as a result of familial increased susceptibility of hair follicles to androgen secretion following puberty. Two areas of the scalp are commonly affected in men, as evidenced by a receding frontal and bilateral triangular temple hair lines, and a balding patch on the vertex, which may progress to complete male pattern baldness. In females, a diffuse partial hair loss in the central parietal area of the scalp with preservation of the frontal and temporal hair lines is most common.
One of the more common therapies for alopecia is minoxidil, which has been proven to be an effective hair growth stimulator that can both maintain and increase scalp hair counts. Minoxidil was first used as a patent antihypertensive drug. It was later discovered that Minoxidil had positive effects on hair growth when applied topically to the scalp. Minoxidil was first mass marketed as Rogaine® lotion by Upjohn, Inc. for the treatment of hair loss in the late 1980s. Rogaine® lotion still remains the only FDA approved topical medication for the treatment of hair loss in the United States, as of this date. The directions associated with traditional minoxidil lotions, such as Rogaine® lotion, now manufactured by Johnson and Johnson, is that a total dose of 1 mL minoxidil topical solution should be applied twice per day to the scalp, beginning at the centre of the affected area. Each 1 mL of minoxidil solution contains 20 mg of minoxidil for 2% solutions and 50 mg of minoxidil for 5% solutions. This dose should be used regardless of the size of the affected area. The total daily dose should not exceed 2 mL. The method of application varies according to the disposable applicator used. Packages contain several applicator options, including a dropper marked with a 1-mL calibration, a spray applicator, and an extended-spray applicator, which is ideal for long hair. Six pumps of the applicators release 1 mL of minoxidil. Because systemic absorption could affect blood pressure, the patient should not inhale the aerosol generated by the spray applicators.
Although the following systemic effects have not been associated with the topical use of minoxidil topical solution, there is some absorption of minoxidil from the skin and the potential exists for systemic effects such as tachycardia, angina, edema or potentiation of the orthostatic hypotension produced by guanethidine. Systemically absorbed minoxidil is secreted in human milk.
The application times for minoxidil should be at least four hours apart, suggesting that the best times to apply the product would be right after the morning shower, and before bed at night. The traditional 5% minoxidil Rogaine® lotion utilizes as much as 50% by volume propylene glycol (20% v/v of propylene glycol for 2% minoxidil) as a vehicle for extending the delivery of the active medication to the scalp, and for ensuring that the applied minoxidil is evenly spread across the affected area and easily absorbed into the skin. Propylene glycol and ethanol alcohol are also used to solubilize minoxidil. The problem associated with smearing copious amounts of propylene glycol on one's scalp is that it leaves the hair and scalp with a greasy texture for an extended period of time after the application. The resulting appearance is often unflattering. It also leaves the hair looking matted down and even thinner than it really is, which may be considered an unfortunate step in the wrong direction for a hair loss treatment.
Another issue associated with propylene glycol is that it can irritate the user's scalp, resulting in itching, flaking, redness of the scalp, oiliness of the scalp, excessive dandruff, and even peeling in some cases. Because of these effects, the use of traditional minoxidil solution was not an option for many hair loss sufferers, and glycerine versions of the popular medication have been developed, available by prescription from Minoxidil.com.
Johnson and Johnson is currently marketing Rogaine® Foam, which delivers minoxidil to the scalp in a manner that is just as effective as the traditional propylene glycol based minoxidil lotions, but without some of the mess or unpleasantness. Rogaine® Foam is designed to retain its “foamy” texture at room temperature, but quickly liquefies, spurring quick skin absorption at body temperature.
Fast skin absorption by Rogaine® Foam means that the active ingredient of Rogaine® Foam, minoxidil, will be readily absorbed into the hand of the user, where it clearly is not intended to be absorbed. Over-absorption of minoxidil can result in vision changes, chest pain and fast or irregular heart beat. Women exposed to over-absorption of minoxidil may experience additional unwanted facial hair growth. Additionally, minoxidil may pass from mother to child through breast milk. It is for these and other reasons that the Rogaine® Foam package insert suggests that the user rinse his or her hand under cold water before applying the foam, to slow down absorption of the active ingredient into the hand. This, of course, requires another step (or two, if the user also dries his or her hand, as recommended by the manufacturer) in the application of the medication. It may also dilute the concentration if one does not immediately dry one's hand after wetting, and before applying the foam. In addition, hair does feel a little stiffer after the application of the Rogaine® Foam and the smearing of the foamy application, with or without a wet hand, can also mat down hair styles, making them less natural looking.
Accordingly, there remains a need for further dispensing systems and methods for scalp medications, including minoxidil and other products, such as DHT inhibitors, finesteride (Propecia®), copper peptides (Tricomin® and Folligen®), other DHT inhibitors (Dutasteride®), all-around treatments or combinations (Proxiphen®) androgen receptor blockers (Spirondactone®), corticosteroids, vitamin A derivatives (Retin-A®), tretinoin, azelaic acid, zinc, B6, grape seed extract, nicotinate and/or progesterone, which are easy to use and provide a more natural appearance than conventionally applied propylene glycol-based and foam-based products delivery systems.